Bacterial and fungal fouling is known to cause damage or lead to contamination of surfaces such as of medical devices, hospital theatres, teeth and kitchen surfaces, swimming pools, industrial pipes, architectural structures, and ships hulls. Such contamination can lead to microbial infection and remains one of the most serious problems associated with biomaterials. Patients using medical devices and appliances ranging from orthopedic pins, plates and cardiac implants through to wound dressings and urinary catheters must constantly guard against bacteria infection. It is also known that the number of invasive fungal infections is steadily increasing world wide. Therefore there continues to exist a strong need for improved antimicrobials which provide effectiveness against not only bacterial contamination but also fungal contamination and which are easily incorporated within or onto materials including biomaterials to provide the needed antimicrobial effect whilst causing little or no adverse effect on the physical properties of the material such as appearance, strength and impact resistance.
The use of particular polymers as antimicrobial agents is known in the art. Further it is known that polymers of tert-butylaminoethyl methacrylate (tBAEMA) have antimicrobial activity.
For example, European Application No. 0204312 discloses non-fugitive antimicrobial activity of acrylic copolymers with aminoalkyl(meth)acrylic monomers including dimethylaminoethyl methacrylate (DMAEMA), diethylaminoethyl methacrylate (DEAEMA) and tertiarybutylaminoethymethacrylate in protonated form.
U.S. Pat. No. 5,209,922 discloses an antifungal block copolymer of vinyl lactam with quaternized aminoalkyl acrylamide.
U.S. Pat. No. 3,592,805 discloses preparation of fungicidal compounds obtained by complexing perhalogenated acetone derivatives with amine compounds including tBAEMA.
U.S. Pat. No. 5,967,714 discloses antimicrobial polymers prepared by graft copolymerization of tert-butylaminoethyl methacrylate with one or more aliphatically unsaturated monomers on plastic substrates.U.S. Pat. No. 6,096,800 discloses a process for the preparation of antimicrobial plastics by carrying out polymerization of t-butylaminoethyl methacrylate (tBAEMA) in the presence of plastic articles.
U.S. Pat. No. 6,790,910 discloses water-insoluble homopolymers of aminoalkyl methacrylates such as tBAEMA and DEAEMA having antimicrobial activity.
The above references however have certain disadvantages. For example, the high molecular weight aminoakylmethacrylate polymers described above are not easily incorporated into materials, especially polymeric materials. High molecular weight polymers are generally quite viscous and thus may require solubilization by solvents before incorporation onto or into a material. Grafting of the polymer onto a material requires an additional grafting step. While grafting may impart antimicrobial activity and prevent leaching, the grafting step may otherwise adversely impact the physical properties of the grafted material.
While the references above teach that polymers of aminoalkyl methacrylates have antimicrobial imparting effects against bacteria, the above polymers fail to provide as effective antifungal protection against multicellular mold fungi, especially on Aspergillus niger. 